IRS Publication 535 (2020), Business Expenses
https://www.nolo.com/legal-encyclopedia/should-an-independent-contractor-form-an-llc.html
https://www.nolo.com/legal-encyclopedia/electing-s-corporation-tax-status-single-member-llc.html
S Corp Capital Gains: Everything You Need to Know
What is better for a consulting company S Corporation or LLC?
What entity is better for consulting purposes, Llc or S-Corp?
S Corp Basis Worksheet | UpCounsel 2021
S Corporation Stock and Debt Basis
Worksheet for Figuring a Shareholder’s Stock and Debt Basis
LLC owners may also be eligible for a new income tax deduction for pass-through entities established by the Tax Cuts and Jobs Act. Starting in 2018, the owner of a pass-through entity, including a single or multi-member LLC, can deduct for income tax purposes up to 20% of the net income from the entity.
https://www.investopedia.com/taxes/trumps-tax-reform-plan-explained/
https://www.congress.gov/115/bills/hr1/BILLS-115hr1enr.pdf
https://www.irs.gov/tax-reform
https://www.congress.gov/bill/115th-congress/house-bill/1/text
https://www.irs.gov/retirement-plans/one-participant-401k-plans